gdb/common/scoped_mmap.h

   1 /* scoped_mmap, automatically unmap files
   2
   3    Copyright (C) 2018 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef SCOPED_MMAP_H
  21 #define SCOPED_MMAP_H
  22
  23 #include "config.h"
  24
  25 #ifdef HAVE_SYS_MMAN_H
  26
  27 #include <sys/mman.h>
  28
  29 /* A smart-pointer-like class to mmap() and automatically munmap() a memory
  30    mapping.  */
  31
  32 class scoped_mmap
  33 {
  34 public:
  35   scoped_mmap () noexcept : m_mem (MAP_FAILED), m_length (0) {}
  36   scoped_mmap (void *addr, size_t length, int prot, int flags, int fd,
  37                off_t offset) noexcept : m_length (length)
  38   {
  39     m_mem = mmap (addr, m_length, prot, flags, fd, offset);
  40   }
  41
  42   ~scoped_mmap ()
  43   {
  44     destroy ();
  45   }
  46
  47   scoped_mmap (scoped_mmap &&rhs)
  48   {
  49     destroy ();
  50
  51     m_mem = rhs.m_mem;
  52     m_length = rhs.m_length;
  53
  54     rhs.m_mem = MAP_FAILED;
  55     rhs.m_length = 0;
  56   }
  57
  58   DISABLE_COPY_AND_ASSIGN (scoped_mmap);
  59
  60   void *release () noexcept
  61   {
  62     void *mem = m_mem;
  63     m_mem = MAP_FAILED;
  64     m_length = 0;
  65     return mem;
  66   }
  67
  68   void reset (void *addr, size_t length, int prot, int flags, int fd,
  69               off_t offset) noexcept
  70   {
  71     destroy ();
  72
  73     m_length = length;
  74     m_mem = mmap (addr, m_length, prot, flags, fd, offset);
  75   }
  76
  77   size_t size () const noexcept { return m_length; }
  78   void *get () const noexcept { return m_mem; }
  79
  80 private:
  81   void destroy ()
  82   {
  83     if (m_mem != MAP_FAILED)
  84       munmap (m_mem, m_length);
  85   }
  86
  87   void *m_mem;
  88   size_t m_length;
  89 };
  90
  91 /* Map FILENAME in memory.  Throw an error if anything goes wrong.  */
  92 scoped_mmap mmap_file (const char *filename);
  93
  94 #endif /* HAVE_SYS_MMAN_H */
  95 #endif /* SCOPED_MMAP_H */